Currently, only the first Tremors movie is available on Blu-ray, but Universal has announced the Tremors Attack Pack, a collection of all four Tremors films together on Blu-ray. The set is due out on September 17th, includes a handful of bonus features, as well as DVD versions of each movie:

"The relentless, man-eating creatures from below the ground are back! Including all four Tremors films in one action-packed collection, The Tremors Attack Pack is the ultimate sci-fi adventure that will leave you on the edge of your seat! Starring Kevin Bacon, Michael Gross, Fred Ward and Reba McEntire, the race is on to overcome these slimy subterraneans in an epic battle of man vs. creature."